TY - CONF A1 - Gerrits, Ruben T1 - Fungal biofilms are supported by EPS and protective pigments in their substrate attachment and desiccation tolerance N2 - Rock-inhabiting fungi are known to colonise air-exposed substrates like minerals, photovoltaic panels building facades and monuments, withstanding the various stresses these extreme habitats are known for. Here we show how both colonisation and stress resistance are linked to the properties of the fungal cell surface. By deleting genes involved in the synthesis of melanin and carotenoid pigments of the model rock-inhabiting fungus Knufia petricola via CRISPR-Cas and comparing the behaviour of the gene-deletion mutants with the wild type (WT), we studied the role of these genes in mineral colonisation and stress sensitivity. The extracellular polymeric substances (EPS) of biofilms of the WT and mutants were extracted, quantified and chemically characterised. We observed that the absence of melanin affected the quantity and composition of the produced EPS: melanin-deficient mutants synthesised more EPS containing fewer pullulan-related glycosidic linkages. Moreover, in mineral dissolution experiments, these mutants showed a lower ability to colonise the mineral olivine. We hypothesise that not melanin, but the pullulan-related linkages enabled the melanin-producing strains to attach more strongly to the mineral. Moreover, ICP-OES analysis of the aqueous mineral-derived solutes showed that biofilms of the K. petricola mutants which could attach were able to dissolve the olivine faster than those that could not. The same mutants were also characterised by their sensitivity to desiccation stress: only the mutant deficient in both melanin and carotenoid synthesis was more sensitive to desiccation compared to the WT, indicating that a combination of both pigments is critical to withstand desiccation. Overall, these results show the critical role of the cell surface in the specific capacities of rock-inhabiting fungi. T2 - Biofilms 10 CY - Leipzig, Germany DA - 09.05.2022 KW - Bio-weathering KW - Desiccation KW - Fungal biofilms PY - 2022 AN - OPUS4-56675 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gerrits, Ruben T1 - The role of melanin in fungal mineral weathering and metal corrosion N2 - Melanins are organic pigments produced by most fungi. These organisms either fix these pigments in their cell wall or secrete them into their extracellular environment to protect themselves against an array of physicochemical stresses (e.g., UV irradiation, desiccation, ...). Melanin can adsorb metals like Fe. How this affects fungal uptake of Fe and deterioration of Fe-containing minerals and metals is however less known. To study this, we use the model fungi Knufia petricola A95, a rock-inhabiting fungus known to deteriorate minerals and have melanised cell walls, and Amorphotheca resinae, able to contaminate fuel tanks, secrete melanin and corrode metals. In K. petricola, we have deleted genes involved in melanin production and Fe uptake using CRISPR/Cas. Through comparison of the geochemical signatures of these gene deletion mutants with those of the wild type (WT), we explore the specific mineral/metal deterioration mechanisms of melanised fungi. Fe isotope signatures of the biomass of melanin- and Fe uptake-deficient mutants of K. petricola revealed that Fe adsorbed either directly onto melanin or after being reduced by Fe reductases. Importantly, once adsorbed to melanin, Fe could not be mobilised and taken up into the cell: both the WT and its melanin-deficient mutant, previously grown at Fe replete conditions, showed similar growth at Fe deficient conditions. Olivine dissolution experiments revealed that Fe oxidation inhibits dissolution. K. petricola was able to enhance dissolution when this inhibition is strongest (at pH 6) and prevented dissolution when this inhibition is weakest (at pH 4). The fungus therefore dissolves olivine by interacting with the oxidised Fe at the olivine surface. However, Fe uptake did not seem to be involved: mutants deficient in various Fe uptake mechanism dissolved olivine at the same rate as the WT. This indicates that Fe adsorption onto melanin might play a key role. This is also shown by K. petricola’s ability to enhance olivine dissolution even further if secreting a melanin precursor and A. resinae’s corrosion of carbon steel whilst secreting melanin. Combined, our results imply that the Fe adsorbed to melanin cannot be taken up but enables fungi to deteriorate Fe-containing substrates at a higher rate. T2 - Goldschmidt 2023 Conference CY - Lyon, Frankreich DA - 10.07.2023 KW - MIC KW - Bio-weathering KW - Olivine PY - 2023 AN - OPUS4-58523 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gerrits, Ruben T1 - Genetic engineering of melanised fungi to study the role of melanin in mineral weathering and metal corrosion N2 - Melanins are organic, dark pigments produced by many organisms. Fungi either fix these pigments in their cell wall or secrete them into their environment to protect themselves against an array of physicochemical stresses (e.g., UV irradiation, desiccation, ...). However, melanins can also adsorb metals like iron and therefore might have a role in the fungal capacity to deteriorate iron-containing minerals and metals. To study this, we focus on the fungi Knufia petricola, a rock-inhabiting fungus with melanised cell walls which deteriorates minerals, and Amorphotheca resinae, a soil-borne fungus able to secrete melanin, degrade alkane-containing fuels, and corrode metals. The broader significance of this work lies in the mitigation of climate change via the negative emission technology enhanced rock weathering for the former to the mitigation of corrosion of biofuel infrastructure for the latter. Genes of K. petricola involved in melanin synthesis and iron uptake were deleted and down- and up- regulated to generate strains with a different melanin content and ability to take up iron. These strains and the wild type (WT) were exposed to a growth solution containing the iron-magnesium silicate olivine of which dissolution rates were obtained by measuring aqueous Mg concentrations using ICP-OES. Thus, the specific mineral deterioration mechanisms of melanised fungi were identified. Abiotically, these experiments showed that iron oxidation at the surface inhibits olivine dissolution. K. petricola was able to enhance dissolution when this abiotic inhibition is strongest (at pH 6) but prevented dissolution when this inhibition is weakest (at pH 4). The fungus therefore dissolves olivine by interacting with the oxidised iron at the olivine surface. Its iron uptake pathways do not seem to be involved as mutants deficient in iron uptake dissolved olivine at the same rate as the WT. The higher dissolution rates of a mutant which secretes a melanin precursor and the lower rates of a melanin-deficient mutant, however, indicate that the iron-adsorbing and -reducing capacities of melanin play a key role. This hypothesis is further supported by carbon steel corrosion experiments with six strains of A. resinae isolated from anthropogenic and natural environments. Their varying ability to secrete melanin correlated with their corrosion rates. We now plan to develop CRISPR/Cas9-mediated genome editing techniques for A. resinae to figure out whether this correlation is also a causation. In summary, our data show that the iron-binding capacity of melanins enables fungi to deteriorate iron-containing substrates at a higher rate. T2 - IBBS19 CY - Berlin, Germany DA - 09.09.2024 KW - Black fungi KW - Weathering KW - Corrosion PY - 2024 AN - OPUS4-61171 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gerrits, Ruben T1 - Quantifying and modelling growth of a subaerial black fungus N2 - Environmental, black fungi are known for their oligotrophic lifestyle and melanin production and are ubiquitous colonisers of natural and anthropogenic subaerial surfaces like marble monuments, washing machine soap dispensers and solar panels. Even though their growth is generally unappreciated, prevention or inhibition thereof is still to be accomplished. We have chosen the genetically amenable, black fungus Knufia petricola as a model species to study these organisms. Our goal is simple: the quantitative description of its growth on various environmental conditions to create a mathematical model using the iDynoMiCS 2.0 platform which could allow the development of a mitigation strategy. The conditions to be tested are the quantity and type of carbon and nitrogen sources, the pH and the presence of neighbouring colonies. First results showed that colonies grown on agar have the highest extension rates at pH 5, 0.01M NO3 or NH4, and 0.1M glucose or sucrose. Interestingly, extension rates but also CO2 production was unaffected by an increase in the concentration of the C-source from 0.01M to 0.1M. On a microscale, we observed that medium containing more C resulted in a higher quantity of branches produced by a single cell and not in a higher single cell growth rate. This rapidly results in a more compact microcolony versus the more extended colonies on C-deficient media. We believe that such deeper knowledge on the growth of black fungi will help mitigate their material colonisation and deterioration. T2 - IMC12 CY - Maastricht, Netherlands DA - 09.08.2024 KW - Black fungi KW - Modelling KW - Carbon and nitrogen limitation PY - 2024 AN - OPUS4-61170 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gentzmann, Marie T1 - Investigation and comparison of Scandium species in different European bauxite residues by combination of novel analytocall tools N2 - In recent times, as the need for new high-tech materials is growing steadily to fulfil future sustainability goals, more and more looks turn towards industrial waste streams as potential sources of valuable metals. Bauxite residue (BR), accumulating during alumina production, is one of the major waste streams in the metal industry. Suitable re-use possibilities for BR are intensively investigated including approaches for the recovery of scandium (Sc). This transition metal, even though rarely recognized by the broader audience yet, has recently gained the interest of e.g. aerospace industries and SOFC-producers since its use is strongly improving the performance and durability of the respective materials. Even though many sources classify Sc as one of the REE, there are many aspects, such as its ionic radius, which significantly differentiate Sc from the REE and cause its behaviour to be distinct as well. The large ionic potential (radius/charge) causes Sc to be incompatible in most rock forming minerals, which results in generally low concentrations in the earth’s crust and rare occurrences of natural Sc-deposits. The general occurrence of enriched concentrations of Sc in some BRs compared to the earth’s crust is known for some time now and has especially been investigated for Greek materials. However, the (geo)chemical and mineralogical behaviour, the Sc speciation, the association and the variation of Sc occurrences in BRs of different origin is still not fully understood. This study aims to gain better knowledge on the different kinds of Sc-occurrences and their possible impact on future recovery schemes. We therefore apply a diverse set of analytical methods including novel measurement techniques such as X-ray absorption near edge structure (XANES) spectroscopy as well as standard techniques such as electron microprobe analyses, and Raman spectroscopy on BRs from Germany, Hungary and Greece. Information on the local distribution of Sc is determined by high-resolution laser ablation – inductively coupled plasma – mass spectrometry (LA-ICP-MS) mappings. Sc in Greek BR seems to have an affinity towards Fe-Phases such as Goethite and Hematite. However, whereas some of these phases show distinct enrichment of Sc, others are particularly barren, which might be a result of the different input materials. By means of XANES measurements it was possible to show that Sc in the Greek samples occurs adsorbed on the surface of those Fe-Phases, likely in the form of amorphous Sc-hydroxide or -oxyhydroxide or can be incorporated into the crystal lattice as well. The general affinity of Sc to those kinds of phases has been reported for natural rocks such as laterites before, where similar investigations were made using the XANES method [8]. Likewise, the Fe-association has been observed for Greek BR by Vind et al. [7]. Hungarian BRs show similar results as the Greek samples and LA-ICP-MS mappings show distinct Sc enrichment rims surrounding mineral particles. In German BR, Fe as well as Ti-phases occur to be partially enriched in Sc. Depending on the original primary bauxite, the source rock of the bauxite and the bauxite processing route, it is likely that many different parameters influence the occurrence and species of Sc in the BR. Theoretically, it either can therefore remain within its original carrier or can be partially or fully redistributed within the BR. Since the processing of the bauxite involves elevated temperatures, pressure and dissolving reagents, it is however very likely that some of the Sc will be redistributed and adsorb on mineral surfaces of smaller and larger particles, making beneficiation steps rather ineffective. The study shows that there is no general rule defining how Sc is associated mineralogically or chemically within BRs. Therefore, the effective development of a recovery method needs a case specific background knowledge on the Sc-species present in the BR of interest. This research has received funding from the European Community’s Horizon 2020 Programme SCALE (H2020/2014-2020) under grant agreement n° 730105. T2 - 3rd European Rare Earth Resources Conference (ERES) 2020 CY - Online meeting DA - 06.10.2020 KW - Red Mud KW - Scandium KW - Bauxite Residue PY - 2020 AN - OPUS4-51570 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Fuentes, Elsa A1 - Prieto, Beatriz T1 - Effect of climate change on phototrophic biofilms colonizing granitic rocks and their biodeteriogenic activity. N2 - Material cultural heritage from NW of the Iberian Peninsula is linked to the use or presence of granite, whether in historical buildings, sculptures, archaeological sites or any other artistic manifestation. This resistant material has the ideal physical characteristics that favor its longevity, but, like any material exposed to the environment, it is susceptible to deterioration. To this respect, environmental changes due to climate change and global change may modify biological colonization-substrate interactions. The main objective of the present research was to analyse the effects of Climate Change, more specifically changes in water availability, increased temperature, increased CO2 concentrations and changes in UV-B radiation patterns, on the survival and biodeteriogenic activity of phototrophic biofilms on granite heritage and the consequences for the built heritage. Both field and laboratory work were carried out. Field studies were conducted on three rural churches to characterise the current biological colonization. A higher proportion of algae than cyanobacteria was identified, with the genera Trentepohlia and Desmococcus standing out among the former. The most common current fungi are lichenised fungi, but black fungal genera such as Catenulostroma, Rhinocladiella and Knufia were also identified. Bacterial genera related to the production of sphinganes, EPS, carotenoids and some causing the so-called pink discolouration are also present. The effect of climate change on the growth and physiological state of the organisms was analysed in the laboratory. For this purpose, mixed biofilms were developed in the laboratory and exposed to changing conditions of temperature, water availability, CO2 and UV-B. A reduction in growth was observed with increasing water restriction, although in the initial colonization process, rock bioreceptivity was shown to be a more important aspect in favoring anchorage and retention of organisms. Temperature was shown to have a growth-enhancing effect when water availability was low, whereas an increase in CO2 only resulted in increased growth under conditions of high-water availability. Increased UV-B produced a reduction in growth, especially at the highest dose (equivalent to the current dose of a west-facing wall in southern Portugal, which is considered as high), while little difference in the physiological state of the organisms was observed at the current doses in Galicia (considered as medium) and southern Ireland (considered as low). Clear changes in microbial composition were observed, with a trend towards increased or greater resistance of cyanobacteria to higher temperature, lower water availability and higher UV-B doses. In addition, all these changes in development, physiological and microbial composition had an effect on the predominant pigments, tending towards more yellowish-brownish colourations, and on the ability of the organisms to generate biodeterioration by affecting ion concentrations on water solutions by enhancing their consumption or adhesion which lead to granite deterioration. Future work should take into account the combination of a greater number of climatic parameters simultaneously and also the possible resistances associated with the nature of the SAB community studied. T2 - 19th International Biodeterioration and Biodegradation Symposium CY - Berlin, Germany DA - 09.09.2024 KW - Biofilm KW - Granite KW - Climate change KW - Biodeterioration KW - Cultural heritage PY - 2024 AN - OPUS4-62271 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Even, Morgane T1 - Formaldehyde emissions from wooden toys: Method comparison and exposure assessment N2 - This study shows that formaldehyde Emission results in micro-scale emission chambers are comparable with results in bigger chambers both for particle boards and wooden toys. On the contrary, the WKI flask method was leading to more variable results depending on sample geometry. Thus, microchambers could be used for reliable routine market surveillance. An exposure assessment led to noticeable formaldehyde indoor air concentration values, pointing out the need for an effective Surveillance of such samples. T2 - Indoor Air 2020: The 16th conference of the international society of indoor air quality and climate CY - Online meeting DA - 01.11.2020 KW - Volatile organic compounds KW - Consumer products KW - WKI flask method KW - Emission chambers KW - Market surveillance PY - 2020 AN - OPUS4-52024 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Even, Morgane T1 - Development of an efficient procedure for the analysis of the emissions of very volatile organic compounds (VVOCs) in emission measurements from construction products and in the indoor air N2 - The ISO 16000-6 standard describes a method for the determination of volatile organic compounds (VOCs) in indoor and test chamber air by sorbent-based active sampling, thermal desorption and gas chromatography coupled with mass spectrometry (GC/MS). It also gives directions to adapt this methodology to very volatile organic compounds (VVOCs). Indeed, toxicologically based guideline values are being implemented for these compounds and it becomes necessary to measure them. But a comprehensive and robust measurement method is lacking. Investigations on the use of gaseous standards, the suitability of chromatography columns, the suitable sorbent combinations and the water removal are required. The talk will highlight the points that need to be explored towards the standardisation of a suitable procedure and provide appropriate preliminary results. T2 - Emissions and Odours from Materials 2021, Certech CY - Online meeting DA - 07.10.2021 KW - VVOCs KW - Analytical method KW - ISO 16000-6 KW - Thermal desorption KW - Gas chromatography PY - 2021 AN - OPUS4-53485 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Even, Morgane T1 - Formaldehyde Emissions from Wooden Toys: Method Comparison and Exposure Assessment N2 - Formaldehyde is considered as carcinogenic and is emitted from particleboards and plywood used in toy manufacturing. Currently, the flask method is frequently used in Europe for market surveillance purposes to assess formaldehyde release from toys, but its concordance to levels measured in emission test chambers is poor. Surveillance laboratories are unable to afford laborious and expensive emission chamber testing to comply with a new amendment of the European Toy Directive; they need an alternative method that can provide reliable results. Therefore, the application of miniaturised emission test chambers was tested. Comparisons between a 1 m3 emission test chamber and 44 mL microchambers with two particleboards over 28 days and between a 24 L desiccator chamber and the microchambers with three puzzle samples over 10 days resulted in a correlation coefficient r2 of 0.834 for formaldehyde at steady state. The correlation between the results obtained in microchambers vs. flask showed a high variability over 10 samples (r2: 0.145), thereby demonstrating the error-proneness of the flask method in comparison to methods carried out under ambient parameters. An exposure assessment was also performed for three toy puzzles: indoor formaldehyde concentrations caused by puzzles were not negligible (up to 8 μg/m3), especially when more conservative exposure scenarios were considered. T2 - OE conference CY - Online meeting DA - 23.03.2021 KW - Formaldehyde KW - Wooden toys PY - 2021 AN - OPUS4-52330 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Even, Morgane T1 - Formaldehydemissionen aus Holzspielzeug: Methodenvergleich und Expositionsabschätzung N2 - Formaldehyd gilt als krebserregend und wird von Spanplatten und Sperrholz emittiert, die bei der Spielzeugherstellung verwendet werden. Die Untersuchungsänter benötigen eine wirtschaftliche und zuverlässige Methode. Die Anwendung miniaturisierter Emissionsprüfkammern wurde getestet und mit größeren Emissionsprüfkammern und die Flaschenmethode verglichen. Eine Expositionsabschätzung wird auch vorgestellt. T2 - 28. WaBoLu-Innenraumtage CY - Online Meeting DA - 10.05.2021 KW - Formaldehyd KW - Emission KW - Spielzeug KW - Methoden PY - 2021 AN - OPUS4-52628 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -